SofiayoudaoicibaDictYouDict[Sofia 词源字典]
Bulgarian capital, Roman Serdica, from the Thracian Serdi people who lived thereabouts. Conquered by the Bulgarians 9c. who altered the name by folk-etymology to Sredeti, which in their tongue meant "center, middle." It got its current name 14c. when the Turks conquered it and converted the 6c. church of St. Sophia into a mosque; the name thence extended to the whole city.[Sofia etymology, Sofia origin, 英语词源]